Reaching selective fluorescence phosphate detection over pyrophosphate with a cerium-based chemosensor in aqueous media

Phosphate ions are important molecules used in critical activities, such as those in agriculture or medicine. However, because of their chemical makeup, sensing them using a chemosensor is difficult. In the past, chemists attempted to solve this issue by creating sophisticated chemical structures as receptors, but with mixed results. Here, using just chemicals that are readily accessible on the market, we establish a straightforward metal extrusion-based fluorescence indicator displacement assay (MEFID) for phosphate detection. Using a fluorophore and cerium ammonium nitrate (CAN), phosphate ions in aqueous solutions are probed. With an average concentration higher than copper and being the most prevalent rare earth on the planet (48 p.p.m.), cerium is an intriguing metal for the identification of analytes. We demonstrate, that the inorganic complex detects phosphate ions in low micromolar concentrations, either spectrophotometrically, by 31P NMR, or with the naked- eye, with high selectivity over common competing anions, including halides, acetate, carbonate, and, remarkably, pyrophosphate. In addition, perturbation of the sensor with phosphorylated molecules such as ATP is minimal. The development of receptors that endures a precipitation offers systems for the purification of surface waters as presented by the probing of environmental samples.